Question drawn from very renowned book RD sharma of class 10th, Chapter no. 4

Chapter name:- Triangles

Exercise :- 4.2

This is very important question of triangle.

We have a triangle ΔABC,

In which D and E are points on the sides AB and AC respectively.

Now For the following case we have to show that DE ∥ BC

It is given that AD = 5.7 cm, BD = 9.5 cm, AE = 3.3 cm, and EC = 5.5 cm.

learning CBSE maths in efficient way

RD sharma, DHANPAT RAI publication

Class 10th, triangle

Given:Length of side AD = 5.7 cm, BD = 9.5 cm, AE = 3.3 cm, and EC = 5.5 cm

To show: Side DE is parallel to BC (DE || BC)Now,

Length of side AD/BD = 5.7/9.5 = 3/5 – equation 1

And,

Length of side AE/CE = 3.3/5.5 = 3/5 – equation 2

Now from equation 1 and 2

AD/BD = AE/CE

So, by the converse of Thale’s Theorem

We get, DE ∥ BC.Hence, Proved